listen for SIGHUP, restart node (reload config file, listen for stdin again, etc) if we receive one

cmd/yggdrasil/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"crypto/ed25519"
 	"encoding/hex"
 	"encoding/json"
@@ -41,15 +42,15 @@ type node struct {
 	admin     *admin.AdminSocket
 }
 
-func readConfig(log *log.Logger, useconf *bool, useconffile *string, normaliseconf *bool) *config.NodeConfig {
+func readConfig(log *log.Logger, useconf bool, useconffile string, normaliseconf bool) *config.NodeConfig {
 	// Use a configuration file. If -useconf, the configuration will be read
 	// from stdin. If -useconffile, the configuration will be read from the
 	// filesystem.
 	var conf []byte
 	var err error
-	if *useconffile != "" {
+	if useconffile != "" {
 		// Read the file from the filesystem
-		conf, err = ioutil.ReadFile(*useconffile)
+		conf, err = ioutil.ReadFile(useconffile)
 	} else {
 		// Read the file from stdin.
 		conf, err = ioutil.ReadAll(os.Stdin)
@@ -180,9 +181,21 @@ func setLogLevel(loglevel string, logger *log.Logger) {
 	}
 }
 
-// The main function is responsible for configuring and starting Yggdrasil.
-func main() {
-	// Configure the command line parameters.
+type yggArgs struct {
+	genconf       bool
+	useconf       bool
+	useconffile   string
+	normaliseconf bool
+	confjson      bool
+	autoconf      bool
+	ver           bool
+	logto         string
+	getaddr       bool
+	getsnet       bool
+	loglevel      string
+}
+
+func getArgs() yggArgs {
 	genconf := flag.Bool("genconf", false, "print a new config to stdout")
 	useconf := flag.Bool("useconf", false, "read HJSON/JSON config from stdin")
 	useconffile := flag.String("useconffile", "", "read HJSON/JSON config from specified file path")
@@ -195,10 +208,43 @@ func main() {
 	getsnet := flag.Bool("subnet", false, "returns the IPv6 subnet as derived from the supplied configuration")
 	loglevel := flag.String("loglevel", "info", "loglevel to enable")
 	flag.Parse()
+	return yggArgs{
+		genconf:       *genconf,
+		useconf:       *useconf,
+		useconffile:   *useconffile,
+		normaliseconf: *normaliseconf,
+		confjson:      *confjson,
+		autoconf:      *autoconf,
+		ver:           *ver,
+		logto:         *logto,
+		getaddr:       *getaddr,
+		getsnet:       *getsnet,
+		loglevel:      *loglevel,
+	}
+}
+
+// The main function is responsible for configuring and starting Yggdrasil.
+func run(args yggArgs, ctx context.Context, done chan struct{}) {
+	defer close(done)
+	// Configure the command line parameters.
+	/*
+		genconf := flag.Bool("genconf", false, "print a new config to stdout")
+		useconf := flag.Bool("useconf", false, "read HJSON/JSON config from stdin")
+		useconffile := flag.String("useconffile", "", "read HJSON/JSON config from specified file path")
+		normaliseconf := flag.Bool("normaliseconf", false, "use in combination with either -useconf or -useconffile, outputs your configuration normalised")
+		confjson := flag.Bool("json", false, "print configuration from -genconf or -normaliseconf as JSON instead of HJSON")
+		autoconf := flag.Bool("autoconf", false, "automatic mode (dynamic IP, peer with IPv6 neighbors)")
+		ver := flag.Bool("version", false, "prints the version of this build")
+		logto := flag.String("logto", "stdout", "file path to log to, \"syslog\" or \"stdout\"")
+		getaddr := flag.Bool("address", false, "returns the IPv6 address as derived from the supplied configuration")
+		getsnet := flag.Bool("subnet", false, "returns the IPv6 subnet as derived from the supplied configuration")
+		loglevel := flag.String("loglevel", "info", "loglevel to enable")
+		flag.Parse()
+	*/
 
 	// Create a new logger that logs output to stdout.
 	var logger *log.Logger
-	switch *logto {
+	switch args.logto {
 	case "stdout":
 		logger = log.New(os.Stdout, "", log.Flags())
 	case "syslog":
@@ -206,7 +252,7 @@ func main() {
 			logger = log.New(syslogger, "", log.Flags())
 		}
 	default:
-		if logfd, err := os.OpenFile(*logto, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644); err == nil {
+		if logfd, err := os.OpenFile(args.logto, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644); err == nil {
 			logger = log.New(logfd, "", log.Flags())
 		}
 	}
@@ -215,33 +261,33 @@ func main() {
 		logger.Warnln("Logging defaulting to stdout")
 	}
 
-	if *normaliseconf {
+	if args.normaliseconf {
 		setLogLevel("error", logger)
 	} else {
-		setLogLevel(*loglevel, logger)
+		setLogLevel(args.loglevel, logger)
 	}
 
 	var cfg *config.NodeConfig
 	var err error
 	switch {
-	case *ver:
+	case args.ver:
 		fmt.Println("Build name:", version.BuildName())
 		fmt.Println("Build version:", version.BuildVersion())
 		return
-	case *autoconf:
+	case args.autoconf:
 		// Use an autoconf-generated config, this will give us random keys and
 		// port numbers, and will use an automatically selected TUN/TAP interface.
 		cfg = defaults.GenerateConfig()
-	case *useconffile != "" || *useconf:
+	case args.useconffile != "" || args.useconf:
 		// Read the configuration from either stdin or from the filesystem
-		cfg = readConfig(logger, useconf, useconffile, normaliseconf)
+		cfg = readConfig(logger, args.useconf, args.useconffile, args.normaliseconf)
 		// If the -normaliseconf option was specified then remarshal the above
 		// configuration and print it back to stdout. This lets the user update
 		// their configuration file with newly mapped names (like above) or to
 		// convert from plain JSON to commented HJSON.
-		if *normaliseconf {
+		if args.normaliseconf {
 			var bs []byte
-			if *confjson {
+			if args.confjson {
 				bs, err = json.MarshalIndent(cfg, "", "  ")
 			} else {
 				bs, err = hjson.Marshal(cfg)
@@ -252,9 +298,9 @@ func main() {
 			fmt.Println(string(bs))
 			return
 		}
-	case *genconf:
+	case args.genconf:
 		// Generate a new configuration and print it to stdout.
-		fmt.Println(doGenconf(*confjson))
+		fmt.Println(doGenconf(args.confjson))
 	default:
 		// No flags were provided, therefore print the list of flags to stdout.
 		flag.PrintDefaults()
@@ -273,14 +319,14 @@ func main() {
 		return nil
 	}
 	switch {
-	case *getaddr:
+	case args.getaddr:
 		if key := getNodeKey(); key != nil {
 			addr := address.AddrForKey(key)
 			ip := net.IP(addr[:])
 			fmt.Println(ip.String())
 		}
 		return
-	case *getsnet:
+	case args.getsnet:
 		if key := getNodeKey(); key != nil {
 			snet := address.SubnetForKey(key)
 			ipnet := net.IPNet{
@@ -337,10 +383,8 @@ func main() {
 	logger.Infof("Your IPv6 address is %s", address.String())
 	logger.Infof("Your IPv6 subnet is %s", subnet.String())
 	// Catch interrupts from the operating system to exit gracefully.
-	c := make(chan os.Signal, 1)
-	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+	<-ctx.Done()
 	// Capture the service being stopped on Windows.
-	<-c
 	minwinsvc.SetOnExit(n.shutdown)
 	n.shutdown()
 }
@@ -351,3 +395,25 @@ func (n *node) shutdown() {
 	_ = n.tuntap.Stop()
 	n.core.Stop()
 }
+
+func main() {
+	args := getArgs()
+	hup := make(chan os.Signal, 1)
+	signal.Notify(hup, os.Interrupt, syscall.SIGHUP)
+	term := make(chan os.Signal, 1)
+	signal.Notify(term, os.Interrupt, syscall.SIGTERM)
+	for {
+		done := make(chan struct{})
+		ctx, cancel := context.WithCancel(context.Background())
+		go run(args, ctx, done)
+		select {
+		case <-hup:
+			cancel()
+			<-done
+		case <-term:
+			cancel()
+			<-done
+			return
+		}
+	}
+}